What is CVE-2018-21030?

CVE-2018-21030 is a medium-severity vulnerability in Jupyter Notebook, classified under Cross-site Scripting. CVSS score: 5.3/10. Published 2019-10-31.

How severe is CVE-2018-21030?

Medium severity. CVSS v3 base score is 5.3 out of 10.

XSS in Jupyter Notebook

CVE-2018-21030

Jupyter Notebook before 5.5.0 does not use a CSP header to treat served files as belonging to a separate origin. Thus, for example, an XSS payload can be placed in an SVG document.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2019-10-31 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.014 (72.8th percentile), scored 2026-10-19.

Low probability of exploitation in the next 30 days, but still tracked. 73rd percentile — 72.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: 0.000

Affected products

Jupyter Notebook

Weakness classification (CWE)

References

github.com/jupyter/notebook/pull/3341 (Patch, Third Party Advisory)
github.com/jupyter/notebook/releases/tag/5.5.0 (Third Party Advisory, Release Notes)
lists.debian.org/debian-lts-announce/2020/11/msg00033.html (mailing-list)

Frequently asked questions

What is CVE-2018-21030?: CVE-2018-21030 is a medium-severity vulnerability in Jupyter Notebook, classified under Cross-site Scripting. CVSS score: 5.3/10. Published 2019-10-31.
How severe is CVE-2018-21030?: Medium severity. CVSS v3 base score is 5.3 out of 10.